／var／logmarcus chiu

for-loop - for-each - (map - reduce - filter - find)

Created on

For-Loop

let nums = [1, 4, 9, 16, 25, 36];
let result = 0;
for (i = 0; i < nums.length; i++) {
  result += numbers[i];
}
// result = 91

For-Each

let nums = [1, 4, 9, 16, 25, 36];
let result = 0;
for each (var num in nums) {
  result += num;
}
// result = 91

Reduce

let nums = [1, 4, 9, 16, 25, 36]
let result = nums.reduce(function(accumulator, num) {
    return accumulator + num;
})
// result = 91

Map

let nums = [1, 4, 9, 16, 25, 36]
let results = nums.map(function(num) {
    return Math.sqrt(num)
})
// results = [1, 2, 3, 4, 5, 6]

Filter

let nums = [1, 4, 9, 16, 25, 36]
let results = nums.filter(function(num) {
    return num > 10
})
// results = [16, 25, 36]

Find

let nums = [1, 4, 9, 16, 25, 36]
let result = nums.find(function(num) {
    return num > 10
})
// result = 16

Mixed (Map - Reduce - Filter - Find)

let numbers = [1, 4, 9, 16, 25, 36]
let result = numbers
	.map(function(num) {
    	return Math.sqrt(num)
	}) // returns [1, 2, 3, 4, 5, 6]
	.filter(function(num) {
		return num > 3
	}) // returns [4, 5, 6]
	.reduce(function(accumulator, num) {
		return accumulator += num
	}) // returns 15
// result = 15